In cooking appliances, especially for commercial or fast food applications, there is a desire to meet two somewhat contradictory goals. The first goal is that the operators of fast food outlets wish to serve as many customers as quickly as possible in order to maximize client satisfaction, and utilization of staff and equipment, to thereby maximize profits. However, there is also a need to ensure that the quality of cooking, in terms of thoroughness of cooked product, is not sacrificed for speed of service of customers. More particularly for some types of food, such as hamburgers, improper cooking can lead to unsanitary and unsafe food being served to customers which can cause sickness and even death in some circumstances. This must be avoided.
One way to speed up cooking, without sacrificing the sanitizing effects that proper cooking has on food, is to cook the food from opposite sides at the same time. This may be accomplished by using a cooking device known as a double contact grill. Such grills have top cooking plates and bottom cooking plates which are attached, for example by means of a hinge or pivot at the back, to allow the cooking plates to be brought together onto food to cook the food and then brought apart from food to allow the cooked food to be removed and served, and for fresh, uncooked food to be placed on the grill, for cooking.
In the past there have been numerous attempts to design such a grill that is on the one hand easy to use and on the other hand practical. However there are several problems with the conventional designs. For example, to alleviate the force that would otherwise be required to lift and lower the top cooking plate there is often provided a spring at the hinge or rear pivot point. Unfortunately springs tend to wear over time, can be difficult to calibrate precisely and are prone to getting dirty, oily and the like. Springs are very difficult to clean. Additionally in such prior designs, there is a problem with the controls, which are typically located below the cooking surfaces and thus are prone to getting covered in grease drippings, splatters and the like. This can create safety problems as well as sanitary problems.
One alternative to using springs is to allow the upper plate to ride in a track, with the raised position being defined by resting the upper plate in a catch in the track. However this can be unstable and requires too much strength to lift larger sized grills.
Another alternative is to use counterweights as proposed in U.S. Pat. No. 4,763,571 to Bergling et al. However the counterweights that are shown in this patent are of a size and a position that they always urge the upper plate into the upper or open position. To keep the cooking plate in contact with the food requires a special catch mechanism which is activated by a timer. Upon a predetermined time elapsing the timer release the catch allowing the plate to pivot upwardly. A cooking weight is provided for, by allowing the upper plate to be free floating relative to the food being cooked. In this manner the full weight of the cooking plate is pressed onto the food. Because this is such a weight, spacers are required to prevent the food from being completely squashed. Different foods require different sized spacers. The spacers have to be inserted and removed according to the type of food being cooked. An inappropriately small spacer results in squashed food. Worse an inappropriately large spacer results in the food not being thoroughly cooked which can lead to sickness, and in some cases death to the person who eats the improperly cooked food.
While the Bergling device eliminates the need for springs, it introduces many complications, including timing devices, catches, spacers, and the prospect of the cooking plate rising up unexpectedly and coming into contact and burning someone. Further, the amount of seating force of the grill on the food is so great as to squish the food. These and other problems make this design generally impractical.